ASSE 4311: Learning Outcome Assessment III/Eng Mechanical Engineering Department

Transcription

1 ASSE 4311: Learning Outcome Assessment III/Eng Mechanical Engineering Department Section# 101 Prepared for Dr. Emad Tanbour Prepared by Jamal J. Al-Saeed ID# Abdullah J. Al-Dossary Ali S. Al-Bayat ID# ID#

2 Statement of Purpose Our project is mainly focusing on the amount of sand in KSA by scooping it from the roads through the basic concepts of snow blowers. By that we will design a Sand Scoop for that purpose by using computer-aided design (CAD) program.

3 Outline Introduction Snow Blowers. Components of a Snow Blower. Scope of Project. Analogy between Two-Stage Snow & Sand Scooper. Computation to determine volume, weight & torque Bearings Selections & Calculations. SolidWorks CAD - Prototype. Conclusion.

4 Introduction The snow blower was invented in 1925 by Arthur Sicard. Snow Blowers has came a long way since then around the globe and its basic principles remain the same. In comparison, a Sand Scooper is a machine that is designed for the purposes of sand clearing.

5 Scope of Project Designing a Sand Scooper Speed: 60 rpm Capacity: 1.6 m wide x 0.6 m high scoop Deferential. Bearings. Shafts. Material Selection. Making of Digital Prototype.

6 Design Approach Group Brainstorming. Gathering Literatures review from different sources. Conceptualization Design. Identification of Critical Components. Sizing and Bearing Calculations. Prototyping using CAD SolidWorks

7 Pillars of Design 1. Material 2. Load (function) 3. Geometry (shape form) Knowing 2 of the 3 will allow us to determine the 3 rd.

8 Problem Statement About 1 / 3 of Saudi Arabia is covered in sand. Sand dunes form by sand drifts and occasional sand storms. In the Eastern Province of Saudi Arabia drift rates reach 30 m 3 /m width annually and dunes up to 25 m in height. An average rate of movement of dune of nearly 15 m per annum. Problem: sand buries pipelines, blocks roads, erodes and surrounds utility foundations.

9 Example Problems

10 Previous Solutions to Problem Most solutions involved controlling the flow of the sand rather than removing or relocating it. Ditching: digging a cut perpendicular to sand drift direction (a very expensive solution). Trenching: dune destruction using bulldozers. Fencing: depositing sands in their vicinity by installing fences perpendicular to the wind direction.

11 Drawing Sketches Figure 2: Front-end Figure 1: Gas-Solid Suspension Figure 3: Overall Process

12 Hand Drawing Sketches Figure 4: Overall View of Shovel Figure 5: Close up view of Shovel & dimensions

13 Figure 6: Shaft Brush Figure 7: Brush & Shaft dimensions

14 Figure 8: Key Hole Figure 9: Tapered Roller Bearing

15 Figure 10: Differential Gear

16 Background on Snow Blowers Snow Blower Types: There are 2 different types of Snow Blowers: Single-stage: Just uses an impeller to force the snow out a chute. Two-stage: Breaks up the snow with metal augers, then uses an impeller to force the snow out a chute.

17 Snow Blower Components A Snow Blower consists of: 1. Frame 2. Motor 3. Impeller 4. Chute In a two-stage blower, there are also metal augers. They spin and break up the snow before it hits the impeller.

18 1. Frame The frame of a snow blower contains all the components and has a handle to push the blower. 2. Impeller The snow blower engine moves the impeller. The impeller is at the front of the blower, it is the first thing the snow hits. The impeller is formed so that when it spins, the snow will go out a chute.

19 3. Chute The chute is attached to the front of the snow blower in direct contact with the impeller. All the snow is pushed through this chute. In most push snow blowers, you can point the chute in different directions. 4. Motor The motor is what drives the impeller. It is attached to the impeller with a belt to make it spin.

20 Snow Blower Components

21 Criteria Efficiency (to maximize sand removal outcome). Quality and reliability of operation. Power (off-road operation i.e. diesel engine power). Resistance (to function in extreme conditions). Safety of user and bystander.

22 Analogy Between Two-stage Snow & Sand Blower

23 Analogy Between Two-stage Snow & Sand Blower

24 Analogy Between Two-stage Snow & Sand Blower

25 Analogy Between Two-stage Snow & Sand Blower

26 Calculations to determine Volume, Weight & Torque Volume = ½ * h * b * l = ½ * 0.6 * 0.65 * 1.6 = m 3 ρ sand = 1922 kg/m 3 Mass = ρ sand * V = 1922 * = Kg Weight = m * g = 600 * 9.81 = N Torque = w * r = 6000 * 0.25 = 1500 N.m

27 Assuming worse scenario, harsh environment, Factor of Safety = 3 Load = 3 * 6000 = N = 18 kn Therefore, Torque = w * r = * 0.25 = 4500 N.m J = π C 4 / 2 = π (0.02) 4 / 2 = 2.5 x 10-7 τ = T c / J = 4500 * 0.02 / 2.5 x 10-7 = 3.6 x 10-6 N/m 2 = 360 MPa

28 SolidWorks CAD - Prototype Figure 11: Shovel Figure 12: Spree Figure 13: Auger Figure 14: Left Brush Figure 15: Whole Brush Figure 16: Right Brush

29 Figure 17: Bevel Gear Side View Figure 19: Bevel Gear Front View Figure 18: Bevel Gear Cross-section

30 Figure 20: Gear Box - Bottom Figure 21: Gear Box - Top Figure 22: Key Hole Figure 18: Journal Bearing Figure 23: Complete Gear Box

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39 Journal Bearing A journal bearing, simply stated, is a cylinder which surrounds the shaft and is filled with some form of fluid lubricant. Journal bearings are considered to be sliding bearings as opposed to rolling bearings such as ball bearings.

40 How to Select A Bearing? Key Components Outer ring Inner ring Rolling element cage By changing these and their combination a rolling bearing can be optimized for almost every application.

41 Types of Bearings? Ball Cylindrical roller Tapered Roller Symmetrical Barrel Roller Asymmetrical Barrel Roller Needle Roller

42 Main stress factors that require spezialized bearings for different applications: hradial load haxial load hspeed hmisalignment htemperature

43 Radial Load When the brush starts to shovel the sand inside the shovel will have a radial force due to the sand and while it s pushing the sand towards the augur using the spiral shape the shaft will experience an axial load.

44 a a a b b b a a a a: Raceway b: Lip The radial load bearing capacity of a rolling bearing depends on the length of the contact line between rolling element and ring.

45 Axial Load

46 The axial load bearing capacity of a rolling bearing can be judged from its contact angle. The axial load is largely determined by the contact angle α; the larger α, the higher the axial load carrying capacity.

47 Inclined Load An inclined load may be split into two components: Radial load F R and Axial load F A. A tapered roller bearing is more suitable or combined axial and radial loading

48 Speed The larger the rolling elements and the higher the speed of the bearing the higher is the centrifugal force pressing the rolling elements against the outer ring raceway.

49 High Speed Effects The speed limitations of tapered roller bearings are dependent upon the permissible operating temperatures of the application and the capability of the lubrication system to effectively remove enough heat throughout its life. Other effects such as moments and centrifugal forces can reduce fatigue life at high speeds but are not taken into account in the basic rating life.

50 Alignment A perfectly aligned bearing is ideal for maximum life and performance. The angle of misalignment for a tapered roller bearing is the difference between the axis of rotation of the cone assembly and the cup axis.

51 Lubrication The proper lubricant reduces friction and prevents wear by providing a particular thickness of film, which separates the bearing surfaces during operation. The required operating viscosity of the lubricant to be used is determined based on the pitch diameter and the rotational speed of the bearing.

52 Operating Viscosity of the Lubricant

53 Rolling Element Bearing Description: Ball or rollers are used to prevent or minimize rubbing. Friction: Rolling coefficient of friction with steel can be ~ Stiffness: Good, but some slack is usually present. Speed: Moderate to high (often requires cooling). Life: Moderate to high (depends on lubrication, often requires maintenance). Notes: Used for higher moment loads than plain bearings with lower friction.

54 Bearing Selection &lang=en&newlink=first&tablename=1_14_1&presentationtype=3&startnum=5

55 Details Dimensions

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57 Calculations for Bearings Life Every care has been taken to ensure the accuracy of this calculation but no liability can be accepted for any loss or damage whether direct, indirect or consequential arising out of the use of the calculation. &action=calc1

58 Bearing Life Equation Bearing life equation is: L 10 = (C / P)10/3 (B / n) a L 10 in hours Where: C = radial rating of the bearing in lbf or N P = radial load in lbf or N. B = factor dependent on the method; B = for the Timken method (3000 hours at 500 rev/min) and 106 /60 for the ISO method a = life adjustment factor; a = 1, when environmental conditions are not considered ; n = rotational speed in rev/min.

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60 Conclusion Doubling load reduces life to one tenth. Reducing load by one half increases life by ten, Doubling speed reduces life by one half. Reducing speed by one half doubles life.

61 Design Outcome

62 Watch Video

63 See Video

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67 Two View - Vertical

68 Two View - Horizontal

69 Top, Trimetric, Front, Right

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72 Project Plan Using Gantt Chart

73 Resources 1. Budynas-Nisbett Shigley s Mechanical Engineering Design, 8 th edition. New York: McGraw-Hill Primis Patents: SKF: &newlink=&prodid=&action=calc1

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